The United States is ordering the relatives of American embassy staffers in Ukraine to leave the country, while giving certain diplomats the option to depart, the State Department said on Sunday, in the latest sign that American officials think Russia is likely to once again invade Ukraine.

The authorized and ordered departures followed assurances by Secretary of State Antony Blinken that the U.S. and allied nations are prepared to counter Russia if it continues its aggressive actions toward Ukraine. Blinken said on Sunday that officials were readying an array of options to respond to various moves by Moscow, although a diplomatic resolution was the preferred path.

“We’re prepared either way,” Blinken said on CNN’s “State of the Union.” “Basically, at this point, the choice is Vladimir Putin’s,” he said of the Russian president, who previously invaded Ukraine in 2014.

Senior State Department officials, in announcing the departure decisions for U.S. Embassy staff and their families in Kyiv, the Ukrainian capital, reiterated earlier warnings that American citizens should avoid travel to the country at this time. U.S. citizens currently in Ukraine should consider leaving by commercial airlines or other available means, the officials added.

The officials declined to offer statistics on how many diplomats and their family members could be affected. They noted, however, that the embassy would stay open, and that the optional departure of some staffers — those American employees who fall into non-emergency categories — wasn’t meant as a knock on the Ukrainian government.

The actions “in no way undermine our support for or commitment to Ukraine,” a senior State Department official said.

The officials did, however, say they remained concerned about internal political stability in Ukraine, which Russia has tried to destabilize through disinformation and other means. In a recent statement, the British Foreign Office said it had evidence that Putin’s government wants to install a Russia-friendly government in Ukraine while it considers invading.

U.S. officials have privately said that American citizens should not expect an Afghanistan-style evacuation operation in Ukraine, and that the situation in Kabul last August was a highly unusual one that should not be considered a precedent. American citizens aren’t required to register with the U.S. government when they go abroad, and State Department officials said they did not know how many were in Ukraine.

There has been a flurry of activity in recent weeks as the Biden administration and European counterparts try to deter Russia from attacking Ukraine, where Russia has built up a massive troop presence along the two countries’ shared border.

The disputes extend well beyond simple questions of territory and local issues; Russia is eager to keep NATO from snuggling close to its own borders, and Putin seems intent on bringing back some of the power and prestige that were lost when Mikhail Gorbachev dissolved the Soviet Union in December 1991.

“We’ll see if we can advance the diplomacy,” Blinken said on Sunday on CBS’ “Face the Nation.” “But even as we’re doing that, we’re preparing — building up defenses, building up deterrence — if Russia chooses the other path.”

Blinken said there were several areas where a compromise could be reached, if Moscow wanted to pursue that pathway, while emphasizing that several items Russia had brought up in discussions were nonstarters — such as barring Ukraine from joining the NATO alliance.

“I was very clear with Foreign Minister [Sergey] Lavrov, as we’ve been, that there’s certain basic principles that we’re not by one iota going to compromise on,” he said on CNN. “Including, for example, NATO’s open door, the right of countries to choose with whom they’ll associate, which alliances they’ll join.”

Blinken also offered assurances that the United States and others would forcefully meet any Russian military maneuver into Ukraine — a point that the administration has stressed repeatedly in the days after President Joe Biden rankled Ukrainian leaders by discussing the possibility of stomaching a “minor incursion.”

“If a single additional Russian force goes into Ukraine in an aggressive way, as I said, that would trigger a swift, severe and united response from us and from Europe,” Blinken said.

Former Secretary of State Mike Pompeo said Blinken made a “much stronger statement” on Sunday than Biden had last week, but added that the current administration needed to go further to ward off Russia.

“If there’s room for doubt, if there is space, Vladimir Putin will drive a truck through that gap,” Pompeo said on “Fox News Sunday.”

Blinken also argued on “State of the Union” that imposing sanctions on Russia now would take away a deterrent effect, contending: “All of the things that we’re doing, including building up in a united way with Europe massive consequences for Russia, is designed to factor into President Putin’s calculus and to deter and dissuade him from taking aggressive action, even as we pursue diplomacy at the same time.”

On “State of the Union,” Sen. (R-Iowa) rejected Blinken’s comments on sanctions — though she said “all options should be on the table” for a response if Russia did invade Ukraine. Discussing the situation from a Cold War perspective, she argued that the U.S. needed to act now in opposition to Russia, rather than wait for an invasion.

“When it comes to pushing back against Russia, we need to show strength and not be in a position of doctrine of appeasement, which seems to be how President Biden has worked his administration,” Ernst said. “So, we do need to go ahead and impose sanctions on Russia now.”

In contrast, Sen. (D-Del.) argued on ABC’s “This Week” on Sunday morning that the Biden White House was deterring Putin from invading Ukraine by pulling together NATO allies and had “invested time and effort in rebuilding our European partnerships,” unlike the Trump administration.

Still, Coons added that he thought Congress should “take up and pass” a bipartisan bill to apply some sanctions now.

“But the very strongest sanctions, the sorts of sanctions that we use to bring Iran to the table, is something that we should hold out as a deterrent to prevent Putin from taking the last step of invading Ukraine,” Coons added.

Joining the flurry of lawmakers responding to Blinken’s comments on Sunday was Rep. (R-Texas), who claimed on “Face the Nation” that “this all started” with the botched military withdrawal from Afghanistan last summer, which resulted in a takeover by the Taliban.

“This is not just about Ukraine,” McCaul said, arguing that “this has broader global ramifications.”

“We’re seen as weak right now because of President Biden, his comments about a limited invasion was somehow acceptable, and that NATO was divided,” McCaul said. “I think one thing he said was true is that NATO is divided, and that’s — Putin’s goal is to divide and weaken NATO. He’s accomplished some of that.”

Politico