WASHINGTON — The Trump administration on Tuesday escalated steps to rein in Iran's activities in the Middle East and North Korea's efforts to evade international sanctions with new penalties against both nations and proxies.

As it winds down its term, the administration announced that it had imposed sanctions on Iran's envoy to Yemen's Houthi rebels, Hasan Irlu, and Al-Mustafa International University for recruiting fighters for the Islamic Revolutionary Guards Corps to foment instability in Yemen and in Syria.

In a separate statement, the Treasury Department said it also was imposing sanctions on six Chinese and Vietnamese companies and four ships for selling and transporting North Korean coal in violation of U.N. sanctions.

The moves come as the administration seeks to step up pressure on governments it opposes in various parts of the world before President-elect Joe Biden takes office in January.

The penalties freeze any assets the targets may already have in or that enter U.S. jurisdictions and bar Americans from doing business with them. Several of those identified for the North Korean violations are already subject to U.S. sanctions. The measures may also subject third country companies and individuals to U.S. sanctions if they are found to be engaging in transactions with them.