The United States warned against any "escalation" in the Middle East in the wake of Israel's war with Hamas, Defense Secretary Lloyd Austin said Sunday, hours after the Pentagon stepped up military readiness in the region. The US has seen a "prospect of significant escalation of attacks on our troops" in the region, Austin said Sunday, adding that the US military was preparing for "the ability to respond." His comments came after the Pentagon said it was upping readiness in the region in response to "recent escalations by Iran and its proxy forces."

SEE HOW THE US MILITARY HAS STEPPED UP ITS READINESS

Russian missile strikes killed at least six postal workers and wounded 17 others when they hit a mail depot in Ukraine's northeastern Kharkiv region, officials said. The strike in the northeastern Kharkiv region on Saturday came as Kyiv declared its positions in the embattled city of Avdiivka were "protected" despite Russian attacks, while Moscow said it had downed Ukrainian missiles targeting the Crimean Peninsula.

UKRAINE COUNTERS WITH ATTACKS ON CRIMEA PENINSULA

Once effectively banned, Chinese science fiction has exploded into the mainstream, embraced by the government and public alike. Its new status was epitomized by this week's Worldcon, the world's oldest and most influential sci-fi gathering, which closed Sunday after taking place in China for the first time. But the wider science fiction fandom has become a rare space where diverse voices have flourished and a vast array of issues -- social, environmental and political -- can be explored.

CHINA WENT ALL OUT IN HOSTING WORLDCON FOR FIRST TIME

What classic film is considered the first science-fiction movie of all-time?

Friday's answer: The US paid France $15 million for 828,000 square miles of land in the Louisiana Purchase -- or roughly 4 cents per acre.