More than a week into Operation Cast Lead, with what began as Israeli airstrikes on Gaza escalating into a ground war, Israel's border to the north remains quiet.
That frontier erupted in 2006, when another Israeli operation in Gaza, one to recover captured soldier Cpl. Gilad Shalit, escalated as a Hezbollah cross-border raid turned into a messy monthlong war.
The consensus in Lebanon has been that this time around, Hezbollah won't join the fight with operations in northern Israel.
"The main question was whether there was going to be a hot front here. It seems pretty clear that won't happen, and that's a relief," said Paul Salem, the Beirut-based head of the Carnegie Middle East Center.
But the second stage of Cast Lead, launched Saturday, renews the chance of Hezbollah coming into a broader conflict.
Amal Saad-Ghorayeb, a political science professor close to Hezbollah, says the group sees the ground invasion as a new phase in the fighting and in its potential involvement. On Sunday, local media reported that Hezbollah militants have been put on "high alert."
"We shouldn't overestimate Hezbollah's restraint. ... At this stage, if Hezbollah is provoked in any way, even a small incident, it could give Hezbollah the justification and pretext to enter the conflict," Saad-Ghorayeb said.
Some analysts see Hezbollah holding back, in part to maintain its political advantage at home. Though Hezbollah has its critics in Lebanon -- above all, its rivals in the anti-Syrian March 14 coalition -- Hezbollah now leads a broad-based coalition that is politically well positioned for this year's Lebanese elections.
Hezbollah, a terrorist group in the eyes of America, Israel and much of the West, could -- together with its allies -- win a majority of seats in parliament.
"At this point it's neck and neck, but they are a dominant force in Lebanon," Salem said. If Hezbollah launched an attack on Israel now, it would risk undermining its cross-sectarian support.
Saad-Ghorayeb describes the relationship between Hezbollah and Hamas as a mix of partner and pupil.
"Hamas is learning from Hezbollah as a resistance model. They are close partners with a very close relationship, but it is one where Hamas is clearly autonomous," she said.
What Hamas has learned reflects Hezbollah's strengths: its hallmarks of indiscriminate rocket fire and guerilla warfare.
"Hezbollah is very optimistic that Hamas would perform well in urban warfare," said Saad-Ghorayeb, who believes Hezbollah has trained Hamas in urban fighting tactics. Hezbollah's confidence that Hamas would do well against Israeli ground forces is another reason analysts say Hezbollah has not joined the battle.
Sunni Hamas and Shiite Hezbollah share an ideology and a set of strategic goals that have superseded their religious difference. Both groups were founded on the fight against Israel and their alliance, along with the support of Iran, has accelerated the buildup of Hamas' firepower and fighting tactics.
"Israel is discovering that [Hamas] capabilities are much more sophisticated than they expected," said Dan Senor, a Middle East expert with the Council on Foreign Relations. Senor believes Hamas has gained tremendously from its ties to Hezbollah and Iran.