High-priority alert based on source significance and keyword relevance.
Context
What happened: Saudi Arabia accused Yemen's Houthis of attacking King Khalid International Airport in Riyadh on Saturday, killing 12 people and injuring 300.
Key numbers: 12 killed, 300 injured.
Why it matters: Al Jazeera framed the attack as a possible significant escalation in the fight between Saudi Arabia and Yemen's Houthis, raising the question of whether the war is entering a new phase.