President Obama met with his National Security Council for more than two hours on Monday night, where they discussed how to respond to the unfolding Russia annexation of the Crimean Peninsula.

The Pentagon has also put on hold all military engagements with Russia, such as “exercises, bilateral meetings, port visits and planning conferences.”

Congress has also begun debating what economic sanctions it could impose on Russia and aid packages it could supply to Ukraine. “We’re usually very bullish about putting a lot of pressure on these regimes that misbehave so that they feel the economic consequences of it,” said House Foreign Affairs Committee Chairman Ed Royce. “So we think we’ve waited too long and we want to accelerate the process.”

In Europe, diplomats considered halting arms sales to Russia and suspending talks with Moscow on unrelated issues, but were more cautious on sweeping punishments. Dutch representatives precluded sanctions, while British documents also indicated that they would reject sanctions as well. Europe’s support for sanctions is key here—the U.S. is not even a top 10 trading partner with Russia.

According to Politico, U.S. Trade Representative Michael Froman’s office suspended talks concerning a bilateral investment treaty with Russia, and visitors from Russia’s agricultural agency were blocked from a planned visit to Washington.

Both congressional foreign relations committees have scheduled testimony from Obama administration officials for Thursday.