The delegation will travel to Britain, Norway, Poland and Estonia to "meet with government officials and military leaders to review and discuss evolving security threats facing Europe as well as opportunities for greater economic cooperation," Ryan's office said in a statement.
The speaker, the most powerful Republican in the House of Representatives and an ally of President Donald Trump, will be joined by House Armed Services Committee chairman Mac Thornberry and four other Republicans, along with two House Democrats.
The US delegation's mission will be seen as particularly poignant in Poland and Estonia, nations near the front lines of the Kremlin's increasingly sharp tone with the West.
The North Atlantic Treaty Organization reinforced its eastern flank in March by deploying British troops and equipment in Estonia, where many citizens remain disturbed by Russia's 2014 annexation of Crimea and the Kremlin's sabre rattling in the Baltic region.
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NATO decided at a July 2016 summit to deploy its troops to the Baltic states and Poland as a tripwire against Russian adventurism in states formerly under Moscow's control.
Ryan's trip was preceded by a delegation to Italy and Portugal this week led by congressman Steve Scalise, the House's number three Republican.