The Yemeni government is denying that Saudi Arabia is bombing targets in Yemen, although I have my doubts. The border is demarcated, but the lines tend to be drawn in sand and I think the potential for Saudi bombs straying across the border whether intentionally or not is high.
This is, as numerous people suspect, a major escalation in the war. What Saudi Arabia will do is still an open question, but sending ground troops across the border would be, in my opinion, a huge mistake.
I am not going to spend much time on the background of the conflict, mostly because I have better things to do than write the same story over and over on this blog and the few of you who follow this, I'm sure, have better things to do than read the same thing over and over. If you haven't read what I have written on the background - run a search for "Huthis" on the blog and look for some of the longer posts as well as the ICG report.
But I will talk about the background that led up to the past couple of days. Much of this involves Jabal Dukhan on the Saudi side of the border. The Huthis claim that on October 2, Yemeni forces used the mountain as a rear base to launch attacks into Sa'dah. They claim that they warned Saudi Arabia about this, but that Saudi continued to provide material support to the Yemeni government while also supporting the government through its not insignificant media reach in the Middle East.
Then on November 2, the Yemeni military again massed a number of troops on the mountain to launch raids back into Yemen. The Huthis responded by crossing into Saudi Arabia and two days later, on November 4, a car full of Huthi fighters came under fire from Saudi border guards. (Notice how for the Huthis the Saudis fired first, while the Saudis claim that the Huthis attacked them. It is impossible to know, or at least for me to know, who fired first.) The Huthis responded killing one Saudi soldier, while another one later died of his wounds.
This incident sparked a large Saudi deployment of troops towards the border, where they believe the Huthis have entrenched themselves in small pockets. The idea is that the Saudis can push them back across the border but, as I mentioned earlier, whether the Saudis can stop at the border is an open questiion. At the same time Saudi fighter planes have been bombing targets, which they claim are in Saudi (they say that they have moved the few local citizens to temporary camps) but which the Huthis say are in Yemen - the Yemeni government has also denied that the Saudis have hit targets in Yemen.
The area they are bombing is so close to the border that even if the Saudi intention is to only bomb suspected Huthi locations inside Saudi Arabia the likelihood that a bomb could go across the border is very high.
Saudi Arabia's increasing involvement in the fighting should be a worrying sign for everyone - some in Yemen seem to think that this will help Salih finally crush the Huthis, but I have my doubts - the last time Saudi attempted to take an active role in the conflict - in the Spring of 2008 - through Husayn al-Ahmar it did not work well. The likelihood of Saudi involvement actually expanding the war instead of ending it is, again in my opinion, rather high.
At the same time, al-Qaeda has to be sitting back and loving this. It just announced that it was behind the ambush of three top security officials in Hadramawt, and while Yemen has started an investigation, al-Qaeda is under little pressure.